1. Soilborne and Arthropodborne Bacterial Diseases
Chapter 12
Soilborne and Arthropodborne Bacterial Diseases

2. 12.1 Soilborne Bacterial Diseases Develop from Endospores
Anthrax is an enzootic disease of large herbivores that ingest the spores while grazing.
Bacillus anthracis produces a capsule and 3 exotoxins.
Figure 12.02A: Bacillus anthracis spores.
© Michael Abbey/Visuals Unlimited
Figure 12.02B: Germinating anthrax spores.
© Dennis Kunkel Microscopy, Inc./ Phototake/ Alamy Images

3. Figure 12.03: Anthrax lesion.
Human forms of Anthrax
Inhalation anthrax was called woolsorter’s disease.
Intestinal anthrax came from contaminated and undercooked meat.
Cutaneous anthrax came from skin abrasions that came in contact with spore-contaminated animal products like shaving bristles that developed into a black necrotic sore.
Agent of bioterrorism through the mail in the US in 2001.
Figure 12.03: Anthrax lesion.
Courtesy of James H. Steele/CDC

4. Tetanus causes hyperactive muscle contractions.
Wounds caused from soilborne contaminants introduce tetanus endospores to tissues.
Clostridium tetani produces a powerful neurotoxin called tetanospasmin that blocks the inhibition of muscle contractions.
Figure MF12.02: Subcutaneous injection.
© Oscar Knott/FogStock/Alamy Images

5. It used to be called lockjaw because of jaw muscle stiffness.
Treated with penicillin and antitoxins.
Immunization with the DTaP vaccine recommended every 10 years for adults after childhood inoculations.
Figure 12.04: Opisthotonos.
Courtesy of CDC

6. Gas Gangrene causes massive tissue damage.
Clostridium perfringens produces a group of toxins and hydrolytic enzymes.
Dead tissue (myonecrosis) blocks blood flow causing gangrene and gas below
the skin.
Treatment is debridement , antibiotics and a hyperbaric oxygen chamber (its an anaerobe).
Figure 12.05: Gas Gangrene of the Hand.
Courtesy of Dr. Jack Poland/CDC

7. Leptospirosis is an emerging zoonotic disease found worldwide.
Leptospira interrogans infection has an endoflagella.
Highest in subtropics
Humans become infected through contaminated animal urine.
Starts with a headache, muscle aches, conjunctivitis and fever and chills that reoccur.
Weil syndrome may develop leading to liver and kidney malfunction
Treatment and prevention is doxycycline
Courtesy of Dr. Jack Poland/CDC
Figure 12.06: Leptospira interrogans.
Figure MF 12.03: Public Health/Environmental Microbiology.
© Andrea Seemann/ShutterStock, Inc.

8. 12.2 Some Bacterial Diseases Can Be Transmitted by Arthropods
Plague can be a highly fatal disease, killing an estimated 25 million people in Europe during the middle ages.
Yersinia pestis is carried in rodents and spread by their fleas.
Figure 12.01: Plague Pit.
© Photos.com

9. Yersinia pestis causes 3 forms of the plague.
Bubonic plague: cells accumulate in the bloodstream and localize in the lymph nodes called buboes.
Septicemic plague spreads through the bloodstream it was known as the black death.
Pneumonic plague is highly contagious by respiratory droplets.
Figure 12.08: Spread of Bubonic Plague in 14th Century Europe.

10. Yersinia pestis is still here
Figure 12.07A: Yersinia Pestis and the Flea Vector.
Courtesy of CDC
Sylvatic Plague is found today in the desert SW among prairie dogs.
Treatable with antibiotics.
Figure 12.07B: Fleas.
Courtesy of CDC

11. Tularemia has more than one disease presentation.
Francisella tularensis infections can involve an extremely small infectious dose causing tularemia or rabbit fever.
Can have a tick vector or be acquired by infected meat, contaminated water or air.
Flu-like symptoms, respiratory disease and swollen lymph nodes.
Figure 12.09: A Tularemia Lesion.
Courtesy of Dr. Brachman/CDC

12. Lyme Disease can be divided into 3 stages.
Figure 12.11: Life Cycle of the Tick.

13. Borrelia burgdorferi is transmitted by the bite of a small tick.
Courtesy of Scott Bauer/USDA
© Phototake/Alamy Images
Figure 12.10AB: Borellia burgdorferi and its tick vector.

14. Figure 12.12: Erythema Migrans.
Stages of Lyme Disease
A bull’s-eye rash begins at the site of the tick bite with fever, aches and pains and flu-like symptoms.
If untreated it can spread to skin, heart, nervous system and joints.
Late stage develops chronic arthritis and swelling in the joints.
Treatable by antibiotics in early stages.
Figure 12.12: Erythema Migrans.
Courtesy of James Gathany/CDC

15. Relapsing Fever is carried by ticks and lice.
Tickborne (endemic) relapsing fever is in the US caused by Borrelia hermisii
Fevers can reoccur as many as 13 times as spirochetes increase in number.
Epidemic relapsing fever is caused by Borellia recurrentis carried by body lice.
All are treated by antibiotics.
Figure 12.13: The Cycles of Relapsing Fever.

16. 12.3 Rickettsial and Ehrlichial Diseases Are Arthropodborne
Rickettsia infections often involve a characteristic rash and tick, lice or flea vectors.
Rocky Mountain spotted fever is caused by Rickettsia rickettsii which is transmitted by hard ticks.
Symptoms are a high fever, headaches and skin rash which spreads.

17. Figure 12.14B: Rocky mountain spotted fever rash.
Courtesy of CDC
Figure 12.14A: R..rickettsii.
© Science VU/Visuals Unlimited

18. Figure MI12: Napoleon’s retreat from Russia.
Epidemic typhus is caused by Rickettsia prowazekii and transmitted by body lice.
It is associated with war, famine and poverty.
Patients have a high fever and rash.
Over 75% die in epidemics.
May reoccur as a milder Brill-Zinsser Disease
Figure MI12: Napoleon’s retreat from Russia.
© Hulton Archive/Stringer/Getty Images

19. Murine (mouse) typhus caused by Rickettsia typhi spread by fleas and lice has a milder fever, headache and rash.
Scrub typhus in Asia and the Pacific is carried by a chigger mite in scrublands, caused by Orientia tsutsugamushi
Rickettsialpox looks like chickenpox spread by mites from mice caused by Rickettsia akari

20. Other Tickborne Zoonoses are emerging diseases in the US
Ehrlichia and Anaplasma species infect different groups of leukocytes.
Human monocytic ehrlichiosis caused by Ehrlichia chaffeensis affect monocytes.
Human granulocytic anaplasmosis caused by Anaplasma phagocytophilum affect neutrophils.
Figure 12.15: Anaplasma phagocytophilum.
Courtesy of Armed Forces Institute of Pathology